Glutamate-gated chloride channels are a family of ligand-gated chloride channels unique to invertebrates. Glutamate-gated chloride channels have been cloned from Caenorhabditis elegans (Cully et al. (1994) Nature 20:371; U.S. Pat. No. 5,527,703), Drosophila melanogaster (Cully et al. (1996) J. Biol. Chem. 271:20187 and U.S. Pat. No. 5,693,492), Haemonchus contortus (Delany et al. (1998) Mol. Biochem. Parasit. 97:177), Lucilia cuprina (GenBank Accession No. AAC31949) and Schistocerca americana (Cohen et al. (1999) 29th Annual Neuroscience Meeting, p. 199). The clones isolated from C. elegans, D. melanogaster and S. americana have been functionally expressed in Xenopus oocytes, and shown to be activated by glutamate and avermectin. (Arena et al. (1991) Molecular Pharm. 40:368; Arena et al. (1992) Molecular Brain Research 15:339; U.S. Pat. No. 5,693,492; U.S. Pat. No. 5,527,703; Cohen et al., supra).
Because glutamate-gated chloride channels are specific to invertebrates, the channels provide a target for insecticides. In particular, the glutamate-gated chloride channels are the target of the avermectin class of insecticides. Avermectins are naturally occurring and synthetic macrocylic lactones that are widely used in the treatment of parasites and insects.
Insects of the order lepidoptera are significant pests, and in particular the larvae are destructive defoliaters. Further, lepidopteran pests are typically harder to control than diptera. Accordingly, there is a need to identify and develop safe and specific insecticides against lepidopteran pests. The present invention addresses this need by providing isolated nucleic acids encoding a lepidopteran glutamate-gated chloride channel, recombinant lepidopteran glutamate-gated chloride channels, and a method of identifying agents that modulate the activity of the channel.
The present invention is directed to an isolated nucleic acid encoding a lepidopteran glutamate-gated chloride channel. In a preferred embodiment the nucleic acid is isolatable from Heliothis virescens. In another preferred embodiment the nucleic acid comprises a sequence encoding the amino acid sequence of SEQ ID NO. 14.
The present invention further comprises vectors comprising a nucleic acid encoding a lepidopteran glutamate-gated chloride channel, and host cells comprising the vectors.
Another aspect of the present invention provides a recombinant lepidopteran glutamate-gated chloride channel, and kits and compositions comprising a recombinant lepidopteran glutamate-gated chloride channel. A method for preparing a lepidopteran glutamate-gated chloride channel is also provided.
In yet another embodiment, the present invention provides a Xenopus oocyte comprising a nucleic acid encoding a lepidopteran glutamate-gated chloride channel, and a Xenopus occyte expressing a functional lepidopteran glutamate-gated chloride channel.
The present invention further provides a method of identifying agents that modulate the activity of the lepidopteran glutamate-gated chloride channel, and agents identified by the method.